Solenoid



w. F. OLIVER May 2641942. 1

SOLENOID Fiied Sept. 18,v 1939 lNVENTakf'f Y Mama: f. 04/1 06 A TTORNEYS.

Patented May 26, 1942 UNITED STATES PATENT! oFFicE f Wallace FrOliver,

SOLENOID South Bend, Ind.; asslgnor to Bendix Home Appliances, Inc., South Bend,

Ind, a corporation of Delaware Application September 18, 1939, Serial No. 295,401 scams. 175-341) There is also included in both forms or the solenoid a combined brace and guide plate It. As seen best in Fig. 8', this guide plate includes lateral extensions I! which form the'head of a T, the body portion l8 being the leg of the T.

The leg of the T is provided withflanges l9. Thisbrace and guide plate 16 is secured to the C-shaped stack of laminations as seen best in Fig. 2 with the head ll secured across the gap of the C and the leg l8 secured .by a rivet 20 to the back of the 0. The flanges I9 extend in contheless thoroughly satisfactory in its operation,

especially from the standpoint of mechanical reliability and smoothness.

Another object of the invention is to provide a solenoid in which the tendency to heat is materially reduced.

Still another object of the invention is to provide a solenoid which will release readily when lie-energized.

Additional objects and advantages of the invention will be apparent from the following description and from the accompanying drawing, in which: V v

Figure 1 is a perspective view of the solenoid of this invention arranged to serve as a pull type solenoid;

Figure 2 is a side view of the yoke structure with the coil and certain other parts omitted for the sake of clarity; I

Figure 3 is a fragmentary sectional view taken on the line 3--3 of Fig. 1; I

Figure 4 is a sectional view taken on the line 4-4 of Fig. 2 with the plunger omitted;

Figure 5 is an enlarged partial side view with the plunger in its innermost position and with parts omitted for the sake of clarity;

' Figure 6 is a plan view of a modified plunger construction;

Figure 7 is a side view of the 6; and

Figure 8 is a perspective view of the combined guide and brace plate.

plunger of Figure Although this invention may take numerous I forms, only one general form, with two adaptations, has been shown. With both adaptations the solenoid includes a stack ll of O-shaped laminations, a stack I2 of straight laminations forming the plunger, a coil l3, and a pair of securing angle strips H. The term (t-shaped" is not intended to mean some one exact form but rather any suitable form having the necessary opening on one side.

tact with the ends of the c and thereby space the plunger from the c-shaped laminations to insure its smooth operation. Furthermore, the remaining lengths of the flanges l9 guide the plunger throughout its stroke, in effect .forming a smooth walled housing therefor. It should be mentioned of course that the braceand guide plates iii are formed of a non-magnetic material such as brass or aluminum so that they will not interfere with the magnetic functions of the solenoid. In effect, the legs I 8 with the flanges l9 form a housing which supports the coil IS on the outside thereof and guides the plunger on the inside thereof.

The securing strips It may advantageously be secured to the stack II by rivets 2| which serve also to hold the several laminations of the stack together. While two securing strips M in the form of angle bars have been shown mounted on the bottom of the solenoid it will be understood that different forms of securing strips could'be employed fastened to the solenoid in different positions to suit different mounting environments.

The plunger illustrated in Figures 1 to 5 is formed by the laminations l2 secured between side plates 24 by rivets 21 or the like. At the outer end the side plates 24 are offset and spaced apart to receive between them a U-shaped coupling link 23 which may be .pivotally connected to the side plates by a pin or rivet 26. The solenoid has been shown as a pull type solenoid which, when energized, draws the plunger into the coil to exert a pull on the end of the link attached to the pin 26. The plunger will be pulled out again by some form oi return spring associated with the link or with the controlled mechanism.

It is desirable to have some means for limiting the movement of the plunger so that it cannot be drawn beyond the position at which adequate force is applied thereto by the solenoid.

In the adaptation of the invention shown in Figs. 1 to 5 the side plates 24 are provided with slots 29 which co-act with lugs 3| formed on plates 32 which are secured outside of the plates It. The plates it are preferably also formed with pressed out lugs 33 extending into the slots 29 and leaving openings 34 through which the lugs 3| project. It will be understood of course that the plate 32, the head I] of plate i3, and the ends of the C-shaped stack of laminations will all be secured together by rivets 33. The plates 32 with their lugs 3| could be omitted if desired.

but when used the lugs 3| serve to reinforce the lugs 33 as will be apparent. In use the lugs 31 and 33 cooperate with the ends of slot 23 to prevent withdrawal of the plunger from the solenoid. I

According to another feature of the invention means are provided to. reduce the air gap between the open ends of the 0 frame and the plunger when the plunger is drawn into the solenoid to reduce heating. As shown, this means is formed by projecting portions 40 on the upper to close the smaller air gap regardless of slight;

inaccuracies in construction.

In order to loosen the plunger when the coil is .de-energized to overcome the effect of any slight residual magnetism, a springis provided acting between the plunger and the 0 frame during the last part'of the inward movement and the initial outward movement of the plunger.-

As shown the spring is formed by a wire loop a 42 having its sides pressed and held between the ends of the laminations I2 and the side plates 24.

On the side of the projections 43 the loop 42 is substantially parallelto the ends of the laminations l2 but on the side of the projections ll the loop is bent inwardly as shown at 43 to engage the end of the 0 frame. Thus the spring action occurs only on one side tending to press the projections 40 into engagement with the adjacent pole face and also at the point where it is most effective .to release the plunger. It will be understood that various other types of springs might be employed but it is preferred to have the spring action at only one side of the plunger.

In view ofthe fact that the .plunger tilts slightly to one side during its final closing movement it would normally not seat properly at its rear end against the frame and so would introduce resistance into the magnetic circuit. To correct this difllculty the rear end of the plunger is cut nection to an operating member such as the link 23 of Figure l. The outer laminations are formed with elongated slots 41 to receive stop pins or lugs such as 31 and 33, the slots being shown as extending through the two outer laminations on each side to give greater depth. 'Although I have described my invention in the preferred embodiment, it is understood that the invention is not limited thereto, but changes and modifications may be made therein, all within the scope of the appended claims.

What is claimed is: 1. A solenoid comprising a magnetic frame having an opening therein defined by spaced pole faces, a magnetic plunger slidable through said opening and clearing the pole faces to provide an air gap, and enlarged portions on said plunger registering with said pole faces when the plunger is in its innermost position to reduce the air gap, one of said enlarged portions being closer to its adjacent pole face than the other whereby the plunger will always be biased toward the same pole face, and resilient means acting between the frame and the plunger on one side only of the plunger during the last part of the inward movement thereof.

2. A solenoid comprising a magnetic frame having an opening therein defined by spaced pole .faces, a magnetic plunger slidable through said opening and clearing the pole faces to provide an air gap, and enlarged portions on said plunger registering with said pole faces when the plunger is in its innermost position to reduce the air gap, one of said enlarged portions being closer to its adjacent pole face than the other whereby the plunger will always be biased toward the same pole face, and a spring carried by the plunger and engaging the frame on one side only of the plunger during the last part of the inward plunger movement.

3. A solenoid comprising a magnetic frame having an opening therein defined by spaced pole faces, a magnetic plunger-slidable through said opening and clearing the pole faces to provide an air gap, enlarged portions on the opposite sides of the plunger to register with the pole faces only after the plunger nears its innermost position, one of said portions being larger than of! at a slight angle as shown in exaggerated I .scale in Figure 2 so that when the plunger tilts tively thicker laminations l6 spaced apart in the central portion of the stack. The .laminations 46 extend beyond the ends of laminations 44 and are perforated to receive a rivet or pin for conthe other, and a spring carried by the plunger and extending laterally therefrom to engage the frame only on the side of the plunger adjacent the smaller enlarged portion during the final part of the plunger inward movement.

4. In a solenoid, a plunger comprising an elongated magnetic member, side plates secured to the opposite sides of said member, said side plates extending beyond one end of the member'and being offset inwardly at said end, and a spring secured between the end of the member and the offset portions of the side plates and extending laterally beyond the member.

5. A solenoid comprising a magnetic frame having an opening in one side, a plunger slidable through the opening and having its inner end seating against the frame, and combined spring and magnetic means to tilt the plunger to one side of the opening during its final inward movement, the inner end of the plunger being cut at an angle to seat flat against the frame when the plunger is tilted.

' WALLACE F. OLIVER. 

